/*
 * $Header: /data/cvs/alin/nanhill-platform/src/main/java/org/nanhill/commons/dbutil/DbUtils.java,v 1.1 2006/09/20 06:55:57 alin Exp $
 * $Revision: 1.1 $
 * $Date: 2006/09/20 06:55:57 $
 * 
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2002-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.nanhill.commons.dbutil;

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;

/**
 * A collection of JDBC helper methods. This class is thread safe.
 * 
 * @author Henri Yandell
 * @author Juozas Baliuka
 * @author Steven Caswell
 * @author David Graham
 */
public final class DbUtils {

	/**
	 * Close a <code>Connection</code>, avoid closing if null.
	 */
	public static void close(Connection conn) throws SQLException {
		if (conn != null) {
			conn.close();
		}
	}

	/**
	 * Close a <code>ResultSet</code>, avoid closing if null.
	 */
	public static void close(ResultSet rs) throws SQLException {
		if (rs != null) {
			rs.close();
		}
	}

	/**
	 * Close a <code>Statement</code>, avoid closing if null.
	 */
	public static void close(Statement stmt) throws SQLException {
		if (stmt != null) {
			stmt.close();
		}
	}

	/**
	 * Close a <code>Connection</code>, avoid closing if null and hide any
	 * SQLExceptions that occur.
	 */
	public static void closeQuietly(Connection conn) {
		try {
			close(conn);
		} catch (SQLException sqle) {
			// quiet
		}
	}

	/**
	 * Close a <code>Connection</code>, <code>Statement</code> and
	 * <code>ResultSet</code>. Avoid closing if null and hide any
	 * SQLExceptions that occur.
	 */
	public static void closeQuietly(Connection conn, Statement stmt, ResultSet rs) {

		closeQuietly(rs);
		closeQuietly(stmt);
		closeQuietly(conn);
	}

	/**
	 * Close a <code>Connection</code>, <code>Statement</code> and
	 * <code>ResultSet</code>. Avoid closing if null and hide any
	 * SQLExceptions that occur.
	 */
	public static void closeQuietly(Connection conn, Statement stmt) {
		closeQuietly(stmt);
		closeQuietly(conn);
	}

	/**
	 * Close a <code>ResultSet</code>, avoid closing if null and hide any
	 * SQLExceptions that occur.
	 */
	public static void closeQuietly(ResultSet rs) {
		try {
			close(rs);
		} catch (SQLException sqle) {
			// quiet
		}
	}

	/**
	 * Close a <code>Statement</code>, avoid closing if null and hide any
	 * SQLExceptions that occur.
	 */
	public static void closeQuietly(Statement stmt) {
		try {
			close(stmt);
		} catch (SQLException sqle) {
			// quiet
		}
	}

	/**
	 * Commits a <code>Connection</code> then closes it, avoid closing if
	 * null.
	 */
	public static void commitAndClose(Connection conn) throws SQLException {
		if (conn != null) {
			conn.commit();
			conn.close();
		}
	}

	/**
	 * Commits a <code>Connection</code> then closes it, avoid closing if null
	 * and hide any SQLExceptions that occur.
	 */
	public static void commitAndCloseQuietly(Connection conn) {
		try {
			commitAndClose(conn);
		} catch (SQLException sqle) {
			// quiet
		}
	}

	/**
	 * Loads and registers a database driver class. If this succeeds, it returns
	 * true, else it returns false.
	 */
	public static boolean loadDriver(String driverClassName) {
		try {
			Class.forName(driverClassName).newInstance();
			return true;

		} catch (ClassNotFoundException e) {
			// TODO Logging?
			// e.printStackTrace();
			return false;

		} catch (IllegalAccessException e) {
			// TODO Logging?
			// e.printStackTrace();

			// Constructor is private, OK for DriverManager contract
			return true;

		} catch (InstantiationException e) {
			// TODO Logging?
			// e.printStackTrace();
			return false;

		} catch (Throwable t) {
			return false;
		}
	}

	public static void printStackTrace(SQLException sqle) {
		printStackTrace(sqle, new PrintWriter(System.err));
	}

	public static void printStackTrace(SQLException sqle, PrintWriter pw) {

		SQLException next = sqle;
		while (next != null) {
			next.printStackTrace(pw);
			next = next.getNextException();
			if (next != null) {
				pw.println("Next SQLException:");
			}
		}
	}

	public static void printWarnings(Connection connection) {
		printWarnings(connection, new PrintWriter(System.err));
	}

	public static void printWarnings(Connection conn, PrintWriter pw) {
		if (conn != null) {
			try {
				printStackTrace(conn.getWarnings(), pw);
			} catch (SQLException sqle) {
				printStackTrace(sqle, pw);
			}
		}
	}

	/**
	 * Rollback any changes made on the given connection.
	 * 
	 * @param conn
	 *            The database Connection to rollback. A null value is legal.
	 * @throws SQLException
	 */
	public static void rollback(Connection conn) throws SQLException {
		if (conn != null) {
			conn.rollback();
		}
	}

	public static String[] getColumnNames(ResultSet rs) throws SQLException {
		ResultSetMetaData meta = rs.getMetaData();
		int cols = meta.getColumnCount();
		String[] columnNames = new String[cols];
		for (int i = 0; i < cols; i++) {
			columnNames[i] = meta.getColumnName(i + 1);
		}
		return columnNames;
	}

}
